To deal with the problems of complex structure parameters
unknown interference factors and lower modeling precision in the Dynamically Tuned Gyroscope (DTG) mechanism modeling by the traditional Subspace Identification Method(SIM)
an improved SIM was proposed. Firstly
the DTG state space model sets were determined and DTG inherent colored noises were discussed. Then
the traditional SIM were modified for the colored noise problem and the orthogonal projection of a data Hankel matrix was used to eliminate the SIM bias of traditional method. Finally
a confidence ellipse was introduced in the numerical simulation to analyze the statistics feature of the modified algorithm. Simulation results indicate that the identified results of modified algorithm are unbiased at different colored noise influences
and the variance is related to the noise strength and data length. The identification experiments show that the identification performance of modified SIM is apparently better than that of the traditional SIM
and the identification fitting degree is more than 90%
which means that the modified algorithm is suitable for the DTG system modeling.
LI X F, YANG G. Integrated design of decoupling and control for dynamically tuned gyroscope lock loop [J]. Nanotechnology and Precision Engineering, 2012, 10(5):439-444. ( in Chinese)
ZHANG L CH, FAN SH X, FAN D P, et al.. Research and implementation of digital control of dynamically tuned gyroscope rebalance loop [J]. Opt. Precision Eng., 2007, 15(12): 1975-1981. (in Chinese)
GANDINO E, GARIBALDI L, MARCHESI S.Covariance driven subspace identification: A complete input output approach [J]. Journal of Sound and Vibration, 2013, 332(26):7000-7017.
ZHANG J B, LU C, HAN Y D. MIMO identification of power system with low level probing tests: applicability comparison of subspace methods [J]. IEEE Transactions on Power Systems, 2013, 28(3): 2907-2917.
HUANG B,DING S X,QIN S J.Closed-loop subspace identification: an orthogonal projection approach [J]. Journal of Process Control, 2005, 15(1):53-66.
MOOR V. Subspace Identification for Linear Systems [M]. London: Kluwer Academic Publishers, 2002.
LIU T, SHAO C, WANG X. Consistency analysis of orthogonal projection based closed loop subspace identification methods [C]. 2013 European Control Conference, ECC 2013, 2013: 1428-1432.
CHIUSO A, PICCI G. Asymptotic variances of subspace estimates [C]. Proceedings of the 40th IEEE Conference on Decision and Control, Orlando, U.S.A, 2001: 3910-3915.
CHIUSO A, PICCI G. Numerical conditioning and asymptotic variance of subspace estimates [J]. Automatica, 2004, 40(4): 677-683.
OKU H, KIMURA H. Recursive 4SID algorithms using gradient type subspace tracking [J]. Automatica, 2002, 38(6): 1035-1043.
OKU H. Recursive subspace model identification algorithms for slowly time-varying systems in closed loop [C]. In Proc. of the ECC’07, Kos, Greece, 2007.
KAREL J K. System Identification [M]. Springer London Ltd, 2011.
ESMAILI A,MACGREGOR J F,TAYLOR P A. Direct and two-step methods for closed-loop identification: a comparison of asymptotic and finite data set performance [J]. Journal of Process Control, 2000, 10(6):525-537.
ZHANG G, LIU PK, ZHANG B, et al.. Design of trajectory tracking controller for precision positioning table driven by linear motor [J]. Opt. Precision Eng., 2013, 21(2): 373-379. (in Chinese)
XIAO Q J, JIA H G, ZHANG J B, et al.. Identification and compensation of nonlinearity for electromechanical actuator servo system [J]. Opt. Precision Eng., 2013, 21(8):2040-2047. (in Chinese)
LJUNG L. System Identification: Theory for the User [M]. Prentice Hall PTR, 1999.